Human Biology - Exam 1 Notes
Human Biology - Exam 1 Notes BIO346
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This 4 page Class Notes was uploaded by Isabelle Zare on Friday February 13, 2015. The Class Notes belongs to BIO346 at University of Texas at Austin taught by Phelps in Fall. Since its upload, it has received 166 views. For similar materials see Human Biology in Biology at University of Texas at Austin.
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Date Created: 02/13/15
Human Biology Exam 1 Notes 1 What is human bio It s why we work the way we do our differences and similarities and evogen 2 Human Genetic Diversity a All cells have 34nm X 6X109 DNA b Human genome project James Watson leads private sector efforts from 19912005 c Government sector efforts Francis Collins Craig Venter 3 Personalized Genomics a Examining 100000 s of small single nucleotides throughout genome b We come to nd that only 17 of human genetics is varied among individuals 4 Alzheimers a 01 frequency in those over age 65 05 in those over age 85 b ApoE Apolipoprotien E has a role in transporting cholesterol into the nervous system and elsewhere in the body ApoE3 common allele variant E2 very rare allele variant E4 somewhat common associated with disease allele variant 1 25 americans have 1 ApoE4 allele 5 Heritability and Association a Heritability number that estimates similarity dues to inheritance b History 1866 Mendel and pea plants 1886 Galton 1918 Fisher 1953 DNA investigated c Variation Measured in st dev and variance average squared diff between measures and mean If xyz VpVgVe VgVaVdVei 1 Vp All variance Vg genetic variance Ve Environmental variance H heritability 2 Broad sense HVgVp Narrow hVaNp ANOVA Regression MZA MZT Full v Half Regression Association studies seek to predict phenotypes based on genotypes not causal 1 On average the 2 best predictors of height add 16 each d Missing Heritability I ii iii iv v vi Need more DNA sequenced Variation is common with weak effects need more people Rare variants causing most variation de novo Structural differences indels CNV Epistasis Gene X environment interactions altogether 40 cont from genech 6 Human Variability and Race a Skin color is 83 heritable Could be a signpost for other variance b Across multiple regions 436 expl and African explained 20 skin color c Remember there is more variance within any one race than there is between any two different ones 7 Population Genetics Drift Gene ow mutation a Evolution changes in allele frequency over time due to drift migrants mutants natse i Modern synthesis Fisher Haldane Wright ii Migration individuals born in a population reproduces in another population this is a type of gene ow iii What affects evolution speed between parts of a once whole population 1 Is there migration 2 How big is the population 3 How long have the population subsets been separate 4 Is selection present iv Also cultural barriers caste community where there is eight times the variance of between separate populations b Haplotypes and Haplogroups i Haplotype set of sequence variants present on the same chromosome at mutation ii Haplogroup haplotypes that share one or more spec variants by common descent more stable 1 We look at mitoch And the Y chromosome because they Omo Kibish Klaises River Malakunanja Monte Verde Pestera cu Yana River o 195KYA o Anatomic 120KYA Expansion through Africa 100KYA Unsucesst ul Middle East 50KYA SE Asia o 45KYA Oceania 14KYA Colonize America o Europe can t recombine iii Ancient Migrations Timeline c Clinal variation geographic differences in selection not isolation by distance which is a neutral force associated with drift and gene ow i Neutral forces leave a mark on the entire genome while selective on one piece 1 Plot p distance against g distance More p variance shows selection more g shows convergence a The residuals d tells you phenol v not explained by drift b Plot residual distance against environmental diff between pops i More environmental diff with more residual adaptation 2 Fisher s microscope analogy a You can reach a mutation selection balance between rate at which new kind of bad things happen as they re taken out 3 Candidate genes loci hypothesized to be under selection a Compare ration withinbetween species to neutral gene if smaller then under selection 8 Evolution of Skin Color adaptation or Drift a Naked skin helps you cool b Dark skin absorbs some UV reduces folate degradation i Thought to have emerged in concert with hairlessness ii MClR gene for dark pigments est 12mya iii Melanocytes give off Vitamin D triggered by sunlight But sun also degrades folate Crit To dev Of embryo and sperm 1 Melanin lters harmful UV preserves folate and reduces vitamin D Stabilizing selection optimizes this a Melanocytes makes eumelanin and pheomelanin light i Happen in low pH melanosomes ii MSH hormone received by MClR Stimulating this hormone release switches to pheomelanin Altered number of melanocyte Making enzymes Hormones that regulate melanin synthesis and sensitivity of hormone receptors 1 Agoutisignaling peptide inhibits MClR b Enzymes for making pigment i Analyzed six different genes ii TYR tyrosinase is an enzyme makes early forms of pigment iii MATP helps traf c this enzyme to right part of melanocyte melanosomes iv OCA2 is an ion transporter on the surface of melanosomes and helps maintain their pH v SLC24A5 is a gene that transports Ca2 ions into melanosomes needed for pigment production vi MClR receptor that triggers deposition of dark eumelanin vii ASIP agoutisignaling peptide is a natural antgonist to MClR and blocks effects of MSH c Used SNP data over 11000 diff lociover 70 genes cont to skin color 9 Pop size 250000 60kya 40kya cave art 12kya ice age ends 6mp then unstable climate First domesticated plants 11KYA Fertile Crescent SW Asia Wheat beans Domestic animals 12KYA cattle 8KYAm sorghum and yams 4KYA a The phenomenon of farming makes 10100 times the calories per acre versus foraging Huge population boom New mutations more successful if selected for b Genes against diabetes happened in Africans Asians and Europeans around agricultural rise In American Indians agriculture is recent 1kya and genetic diversity is low c In Australian aborigines have no agricultural revolution as well as low genetic diversity American Indians and Australians super susceptible to diabetes i Dairy Farming 1 Lactase breaks lactose into glucose and galactose If you have lactase present and ingest lactose in the form of milk cheese etc you will get a glucose surge later a Expressed in small intestine 2 Non coding enhancers responsible for determining where and when gene gets expressed Variation in a distant enhancer predicts lactase persistence
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